Defrosting system



y 1935- w. R. KITZMILLER 2,001,027

v DEFROSTING SYSTEM l Filed Sept. 8; 1931 gwvmtov WIiamR.Kit5miIIerfiiilitllitw nhos'rmd srs'rniw William R. trer, Waynoro, li'a...assignor to Fitch Company, Waynesboro,

tion oil lPeylvania We, a corpora- .dpplication September d, 1931,Serial Ne. 561L804!) 1% Elia.

This inventicn relates to coolers for fluid and especially tothe'defrosting of the type having an agitator r blower for circulatingthe fluid to be cooled overcooling surfaces, which surfaces are d cooledby a fluid of a lower temperature in contact with the cooling surfaceand further provides means for defrosting or removing the ice on theoutside of the cooling surface.

An object of the invention is to provide automatic means of defrostingthe cooling unit when ever the frost has accumulated to an objectionabledegree.

A further object is to provide means for defrosting cooling surfaceswhenever the temperature of the air in the room being cooled has reachedthe desired low point.

In cooling air or any other gas which contains water vapor it is a wellknown fact that when the temperature has dropped below the dew pointsome of the water vapor will condense and freeze on the surfaces of thecooler. This frosting of the cooling surface is objectionable firstbecause the frost is a poor conductor of heat so that when the coolingsurfaces are covered with frost the cooler will no longer absorb heatfrom the surrounding media at the required capacity. Then again theaccumulation of frost on the cooling surfaces may restrict the passageof air over these surfaces or through the cooler so that 30 the fan,blower or agitator will no longer deliver the required amount of air sothat the capacity of the cooler will be greatly reduced.

From the foregoing it will be apparent that it is desirable andnecessary for emcient operation that the frost on the cooling surfacesbe removed from time to time to prevent lowering the chiciency of thecooling unit. In describing the invention language will be used whichparticularly describes the system as applied to cooling air in 40 aroom. The system, however, is in no sense limited to this use but may beemployed in cooling any kind of gas or for cooling a liquid in whichlatter case the liquidto be cooled is delivered against the coolingsurfaces of the cooler so that the whole liquid is brought into heatexchange contact with the cooling media. In carrying out the invention Ishow four diflerent applications or modifications of the principle ofthe invention.

Referring to the accompanying drawing which is made a part hereof and onwhich similar reference characters indicate similar parts,

Figure l is a view in elevation with certain parts showndiagrammatically of the preferred form of the invention,

Figures 2, 3 and 4 are modifications showing the same principle carriedout in a somewhat different structure, and

Figure 5 is a section of a casing housing a circulating fan arrangedeither for sucking or forcing air through a cooler.

In the drawing numeral it indicates a cooler or heat exchange unit ofany suitable construction having an inlet M for the cooling orrefrigerant fluid and an outlet it. In the outlet pipe i2 is placed avalve it: which is here shown as controlled by a solenoid it, thesolenoid being in circuit with lines it and l 6. Instead of a solenoidas a motor valve. A blower or fan ill operated by a motor it circulatesair to be cooled over or through the cooling unit it. The motor it maybe any suitable motor, that shown here being a three phase motoroperated by current from lines i9, and 25, connected through switch 22with power lines 23, 2t and 25 from any suitable source of current. Wirei6 is attached to the wire it in advance of the motor it and circuitthrough the line it is controlled by means of a thermostat switch 26.This may be any suitable thermostatic switch which remains closed solong as the tem- 2 perature in the room is above a predetermined pointbut opens when the temperature has fallen to a predetermined low point.The wire I5 is connected to the wire 2i through a switch 21 which isoperated by any suitable electrical device such for example, as asolenoid 28, the coil of which is in circuit with the wire 2!. Line 2-5is connected by means of a line 29 and. 30 with a wire 23. A temperaturecontrolled switch at is in circuit with the line 29, at, this switchbeing opened when the temperature in the room or in the compartment tobe cooled drops to a predetermined low degree. Switch 22 is held closedby some suitable electrical means as a solenoid 9 so long as the switch3! is closed. When switch 3! is opened the solenoid 9 4 is de-energizedand switch 22 opened to stop motor it.

In operation when frost has collected to an objectionable degree on thecooler Hi this will impede the passage of air blowing through thecooler. and build up a pressure head in front of the fan. This pressurehead will afiect the load. on the motor it. If however the fan isoperated to suck air through the cooler the head on the fan will bedecreased as the passage of air is impeded. In either case the changedload on the motor it may be caused to control the switch 2? so that thisswitch will be opened when the pres sure load has reached acertainpredetermined value. When the circuit through the lines it and I6is interrupted the solenoid It or other motor is de-energized and thevalve I3 is closed. This stops circulation of refrigerant through thecooler III. The fan, however, will continue to operate and its operationwill soon defrost the cooler. As soon as defrosting has been completedthe pressure head on the fan will be removed so that the switch 21 willagain be closed, solenoid I4 energized and valve I3 opened so that thecirculation of refrigerant may again be started. If the temperature inthe room drops to a predetermined low degree temperature con trolledswitch 26 will be opened so that circuit through the lines I5 and I6 andsolenoid I4 will be interrupted so that valve I3 will again be closed tointerrupt circulation of refrigerant through the cooler I6.

Temperature controlled switch 3| is placed in circuit with lines 28 and30 so that when the temperature in the room or chamber to be cooledreaches the desired low degree switch 22 will. be opened to stopoperation of the fan motor I8. This will also break-the circuit throughthe lines I5 and I6 so that the valve I3 will be closed to stopcirculation of refrigerant to the cooler. Should the fan ll be stoppedwith refrigerant still circulating through the cooler, the cooler mightfreeze up. It is necessary therefore to stop operation of therefrigerating fluid when the fan is stopped.

Figure 2 shows a cooler in which the refrigerant inlet 32 is controlledby a valve 33 operated by solenoid or other motor 34. The outlet fromthe cooler 35 is controlled by a valve 36 .operated by solenoid or othermotor 31. A pipe 38 is attached into the outlet connection 39 and avalve 46, controlled by solenoid or other motor 4 I, controls passage offluid through the pipe 38. A pipe 42 connects to the inlet pipe 82 andis controlled by a valve 48 which is operated by a solenoid or othermotor ll. Solenoid 31 is operated by current from lines 45, 48, 49 and52, when switch 86 is in the position shown in Figure 2. A wire 417passes through a solenoid ll to operate it and is attached to wire 86which in turn is attached to wire 88 which is a lead-in wire to a motor58. The motor 58 is operated by current of the three phase type receivedthrough lines it, 59 and 52.

In operation when a pressure or suction head has been built up in thecooler, loading or unloading the fan lit, the load on the motor 58 willbe affected so that solenoid 58 will be operated to break connectionbetween lines 52 and 85 so that solenoid 31 will be deenergized andvalve 36 allowed to close. As is obvious, valve 33 will also be closed.This will stop circulation of refrigerant through the line 39, allowingthe fan 53 to continue to operate to defrost the cooler. Simultaneouslywith closing the valve 36 current will be passed from line 52 throughline 41 and through solenoid 4| so that this solenoid will be energizedto open valve 40. Solenoid 44 is likewise in circuit with line 41 and 48so that solenoid I may likewise be energized to open valve 43. Valves 33and 36 will remain closed so that warm refrigerant may now be circulatedthrough the lines 42 and 38 and the cooler to quickly warm the coolingunit to assist in quickly defrosting this vunit. The defrosting is morequickly accomplished than could be'done by circulating the air in thechamber from the cooler with no auxiliary heat radiating means.

In the form shown in Figure 3 the cooler 55 is supplied with refrigerantflow lines 56 and 51, the line 51 being controlled by a valve 58 whichis operated by solenoid or motor 59. The solenoid 59 in turn is incircuit through lines 66 and 6| with lead-in wires 62 and 63. A switch64 operated by solenoid or other motor 55 is in circuit with lines 6|.Lines 62, 63 and 66 are the usual three-phase lines to a motor 61 foroperating a fan 68. In this form of the invention when the cooler 55becomes covered with frost the load on the fan 68 changes and this loadin turn affects the current through the solenoid 65, so that the switch64 is allowed to open. When switch opens, circuit through the lines and6| is broken, so that the solenoid 59 is de-energized thus permittingthe valve 58 to close. This interrupts circulation so that furtheroperation of the fan 68 forcing or drawing air rapidly through thecooling unit will quickly defrost the cooling unit.

In the form shown in Figure 4 the cooling unit 69 has inlet and outletrefrigerant connections, the latter of which is controlled by valve I6operated by solenoid or other motor II. Fan I2 is operated by motor I3which motor receives its M current through lines I4, I5, I6 connected tolead-in lines I8, I9 and 86 by which 11. A wire 8| is attached to theline I8 and 82 is attached through coil 88 to the line 88. Wires 8| and82 are in series with a thermostatic switch 83 placed in the chamber,the temperature of which is to be regulated, so that when thetemperature falls to the desired low degree switch 83 is-energized toopen the switch I1 which'controls the motor I3 so that the fan will bestopped. A temperature controlled switch 89 is placed in circuit withleadin lines 85 and 86 which latter lines are incircuit with a solenoidII. When the temperature in the chamber to be cooled reaches apredetermined low degree, switch 89 is closed, closing the circuitthrough lines 85 and 86 to energize the solenoid II to close the valveIII. This will interrupt circulation of the refrigerant so that thecooling of the unit 69 will cease simultaneously with circulation of therefrigerant past the cooler. If desired, the solenoid valve I6 may beomitted and a signal used to warn the operator that he should defrostthe cooler. This signal may be a light, a bell or any other suitablesignal. The valve and the lamp are shown in series in Figure 4.

While the fan, blower or pump is described in the foregoing as forcingthe fluid to be cooled through the cooler, the fiuid is frequentlysucked through coolers of this type. Whetherthe fluid is forced orsucked through the cooler does not affect the operation of my invention,and I therefore do not limit myself to forcing the fluid through thecooler.

It will be obvious to those skilled in the art that various changes maybe made in my device without departing from the spirit of the inventionand therefore I do not limit myself to what is shown in the drawing anddescribed in the specification, but only as indicated by'the appendedclaims.

Having thus fully described my said invention, what I claim as new anddesire to secure by Letters Patent, is:

1. A cooler having means for circulating a refrigerant therethrough witha valve for controlling circulation of the refrigerant and a fan formoving a fluid to be cooled over refrigerating surfaces of the cooler, amotor for operating said fan, the load on said motor varying directly inresponse to a pressure head built up through the cooler due to animpeding of the passage of the fluid to be cooled by an accumulation offrost on the said cooling unit, said variation of the load on the motorbeing in control of the said valve whereby the said valve willbe closedwhen frost has covered the cooler to a predetermined degree, the fancontinuing to operate after closing of the valve to thaw out the froston the cooler, substantially as set-forth.

2. In a cooling system for a chamber, a refrigerating unit in saidchamber, means for circulating air in the chamber over saidrefrigerating unit to cool the said air, a refrigerant circuit throughsaid unit having a valvefor controlling the flow of refrigeranttherethrough, means responsive to variations in the load on the motordue to a pressure head built up through the cooler due to frost on thecooler for controlling the said valve, substantially as set forth.

3. In a cooling system for a chamber, a refrigerating unit in saidchamber, means for circulating air in the chamber over saidrefrigerating unit to cool the said air, a refrigerant circuit throughsaid unit having a valve for controlling,

the flow of refrigerant there-through, means responsive to variations inthe load on the motor due to a pressure head built up through the cooler,due to frost on the cooler for controlling the said valve, and meanscontrolled by the temperature in the chamber for stopping operation ofthe fan when the temperature in the chamber has reached a predeterminedlow limit, substantially as set forth.

4. A device for removing frozen substance from a fluid cooler throughwhich a refrigerating fluid is circulated comprising a fan forcirculating fluid to be cooled into contact with the cooler, a motor foroperating said fan, and means for interrupting the flow of refrigerantthrough said cooler, said means being responsive to change in the loadon the motor due to accumulation of frozen substance on the cooler whichresists the passage through the cooler of the fluid being cooled,substantially as set forth.

5. A device for removing frozen substance from a fiuid cooler comprisingmeans for circulating fluid to be cooled in heat exchange relation withthe .cooler, a motor for operating said means, means for causing thecirculation of refrigerant through said cooler, and means responsive tovariation in the load on the motor due to the formation of frozensubstance on the cooler which resists the passage of air through thecooler in control of means for interrupting the circulation ofrefrigerant through the cooler, substantially as set forth.

6. A device for removing frozen substance from a fluid cooler comprisingin combination with a fluid cooler, an agitator for forcing fluid to becooled into heat exchange relation with the cooler and means forcirculating refrigerant through the cooler of means for interrupting theflow of refrigerant comprising a motor for operating said agitator, theload on said motor being increased by the formation of frozen substanceon the cooler which impedes the passage of fluid to be cooled throughthe cooler, means for stopping the said motor and for simultaneouslyinterrupting the circulation of refrigerant through the cooler, saidlast named means operating in response to an increased load on the motordue to the formation of excessive frozen moisture on the said cooler,substantially as set forth.

7. In a device for cooling air in a chamber having a heat exchange unittherein and means for circulating a refrigerant fluid through the unit,an agitator for circulating the air to be cooled in heat exchangerelation with the unit, a motor for operating said agitator, a signalfor indicating when a substance has frozen on the surfaces of the heatexchange unit to an objectionable degree, said signal being operative inresponse to variation in the load on the motor as the formation of thefrozen substance on the heat exchanger impedes circulation of the fluidto be cooled in contact with the heat exchange unit, substantially asset forth.

8. In a cooling system for a chamber, a heat absorbing unit having meansfor circulating a refrigerant therethrough and a valve controlling theflow of refrigerant through the circulating means, means for circulatinga heating fluid through the unit and a valve for controlling the passageof the heating fluid therethrough, an agitator for circulating fluid tobe cooled into heat exchange relation with the said heat absorbing unitan air confining chamber surrounding said agitator, a motor foroperating said agitator, variation in the load on the motor being causedby variation in the obstruction of the passage of the fluid to be cooledabout the coolingunit due to the formation of frozen substance on thesaid unit, the circulation of the cooling fluid and the heating fluidbeing responsive to the said variation of the load on the motor whichdrives the said agitator, substantially as set forth.

9. The method of defrosting a fluid cooler which comprises controllingthe circulation of refrigerant fluid through the cooler in response tothe formation in excess of a predetermined amount of frozen substance onthe cooler, the said control being effected by variation in the load onthe power means for circulating the fluid to be cooled in heat exchangerelation with the cooler, substantially as set forth.

10. The method of controlling the formation of frozen substance on acooler which comprises using the impeding effect of the frozen substanceas it forms on the cooler to vary the load on the power means forcirculating the fluid to be cooled and causing variation of the load onthe power means to vary the circulation of the refrigerant by means ofwhich the cooling unit is cooled, substantially as set forth.

WILLIAM R. KI'IZMILIER.

